Limbic system

Question 1

What is Kluver-Bucy syndrome?

Answer 1

Bilateral lesions of the amygdala (/ medial temporal lobes) resulting in hyperorality (inserting inappropriate objects in the mouth), dietary changes, lack of emotional expression (fear or anger) and hypersexuality

Question 2

What is Korsakoff’s Psychosis?

Answer 2

Degeneration of the mammillary bodies caused by vitamin B1 (thiamine) deficiency as a result of chronic alcohol use.
Associated with anterograde amnesia, confabulation and hallucinations

Question 3

What are the functions of the limbic system?

Answer 3

Sensation and perception of emotions
Visceral response to emotions
Memory formation and consolidation

Question 4

What are the cortical components of the limbic system?

Answer 4

Hippocampus 
Insula 
Cingulate gyrus 
Entorhinal cortex 
Fornix

Question 5

What is the function of the hippocampus?

Answer 5

Memory formation and consolidation

Question 6

What is the function of the insula?

Answer 6

Sets the threshold for emotional responses

Question 7

What is the function of the cingulate gyrus?

Answer 7

Involved in linking sight and smell to memories and previous emotions

Question 8

What is the function of the entorhinal cortex?

Answer 8

Interface between the hippocampus and the cortex

Question 9

What is the function of the fornix?

Answer 9

White matter tract connecting other structures of the limbic system
[Nb. transection of fornix is linked to memory loss]

Question 10

What are the subcortical components of the limbic system?

Answer 10

Amygdala
Mammillary bodies
Hypothalamus 
Olfactory bulb 
Nucleus Accumbens 
Anterior thalamus 
Septal nuclei

Question 11

What is the function of the amygdala?

Answer 11

“Emotional Centre” - involved in evaluating the emotional valence of situations

Question 12

What is the function of the mammillary bodies?

Answer 12

Part of the hypothalamus - role in memory

Question 13

What is the function of the hypothalamus?

Answer 13

Forms connections with multiple nuclei and structures to regulate autonomics, endocrine function and behaviour

Question 14

What is the function of the olfactory bulb?

Answer 14

Processes olfactory input

Question 15

What is the function of the nucleus accumbens?

Answer 15

Central to the reward system, reinforcing pleasant experiences

Question 16

What is the function of the anterior thalamus?

Answer 16

Role in modulating alertness, learning and memory

Question 17

What is the function of the septal nuclei?

Answer 17

Pleasure (sexual/ orgasm sensation)

Question 18

What is Papez’s circuit?

Answer 18

Neural circuit central to the limbic system, which is hypothesised to be the basis of emotion/ perception of emotion

Question 19

What is the pathway of the Papez circuit?

Answer 19

Hippocampus -> Fornix -> Mammillary body -> Mammillothalamic fibres -> Thalamus (anterior nucleus) -> Cingulum -> Entorhinal cortex -> Hippocampus

Question 20

What is the difference between working and long term memory?

Answer 20

Working = temporary retention (e.g. phone number recall)

Long term = lasts indefinitely

Question 21

What is the difference between episodic and semantic memory?

Answer 21

Episodic = events (esp. autobiographical) 
Semantic = facts

Question 22

What is the difference between declarative and non-declarative (procedural) memory?

Answer 22

Declarative = conscious recollection of knowledge (can be episodic or semantic in nature)
Non-declarative (procedural) = learned skills - can be motor (e.g. riding a bike) or language

Question 23

How would someone with hippocampal damage present clinically?

Answer 23

Anterograde amnesia (inability to form new memories)

Question 24

How would someone with damage to the cingulate gyrus present?

Answer 24

Autonomic dysregulation

Emotional disturbances

Question 25

What additional symptoms would someone with Wernicke-Korsakoff’s Syndrome present with compared to someone with Korsakoff’s Psychosis?

Answer 25

Ataxia
Ophthalmoplegia
Confusion